GUY NORRIS / LOS ANGELES
Hypersonic demonstrator's Pacific accident could affect schedule of second mission as finding reason seems unlikely
NASA says the cause of the loss of the X-43A hypersonic demonstrator over the Pacific on 2 June may never be known and suggests that the second attempt to reach Mach 7 with a sister vehicle is now very likely to slip well into 2002, several months behind schedule.
The investigation has focused on the Orbital Sciences Pegasus rocket, meant to boost the X-43A to a higher altitude for the attempt. Seconds after the combined booster and X-43A were launched from NASA's B-52 carrier aircraft, the assembly suffered a structural failure and the pair were destroyed by the range safety officer (Flight International, 12-18 June).
Robert Hughes, chairman of the mishap investigation board from the Marshall Space Flight Center, says the likelihood of finding a single root cause of the loss is "still possible but becoming less probable".
NASA says approximately 85% of the fault tree of several hundred possible or contributing causes have been examined and rejected. It adds the "remaining potential causes mostly dealing with launch vehicle control are being systematically investigated and evaluated".
The agency says it "simply does not know" what impact the uncertainty over the causes of the failure will have on the schedule for the second attempt at flying the scramjet (supersonic combustion ramjet)-powered X-43A. The attempt had already slipped to December 2001 when the accident happened, and is "at best guess now going to be some time in 2002", says NASA. Preparation work on the second vehicle is proceeding slowly.
"They are doing as much as they can to prepare for the next flight, barring any results from the mishap investigation board," says the agency.
Source: Flight International
